01 // Featured
distributed systems9 min
Idempotency keys for POST /charges: retries, duplicates, stored responses, the in-flight lock, the TTL, and which status code to return in each case.
distributed systems9 min
A circuit breaker modeled as an explicit state machine, with thresholds, timeouts, the half-open probe, and how to combine it with retries and jittered backoff. Implemented in TypeScript and Go.
architecture7 min
In-memory fakes instead of mocks, tests that check state instead of calls, contracts shared between adapters, and the shape of the test pyramid in Clean Architecture.
practices7 min
What makes a commit atomic, how to write messages with Conventional Commits, how to split changes with git add -p, and how to fix older commits with fixup and autosquash.
architecture8 min
An order use case with two ports, OrderRepository and PaymentGateway, an in-memory adapter, a Postgres adapter, and the composition root that wires them.
architecture7 min
What the Clean Architecture dependency rule says, why the arrows point toward the domain, what goes in each layer, and the mistakes I see most often in TypeScript services.
Series 3 parts ongoing
From the dependency rule to a testable service, step by step in TypeScript.